A total of 3,175 cases and 69 deaths were recorded,[1][2] although a seroprevalence study estimated that around 800,000 individuals may have been infected during the initial wave of the pandemic.

[3] On 25 April 2009 ten students from Rangitoto College, a secondary school in North Shore City, Auckland, exhibited influenza symptoms on returning from a three-week language trip to Mexico.

All 22 students and three accompanying teachers from the trip and those in close contact with them were placed in voluntary home isolation and treated with oseltamivir.

][8] Confirmed cases have tested positive for the Mexican swine flu strain of influenza type A.

Probable cases had tested positive for influenza type A after possible recent exposure to the Mexican strain.

On 6 June a one-year-old boy from Manukau City was diagnosed with swine flu and several other people who had been exposed to him had gone into isolation.

[15] According to a three-month-long study coordinated by the Australian and New Zealand Intensive Care Research Centre that was published in the New England Journal of Medicine, up to 20% of intensive care unit (ICU) beds overall were occupied by swine flu patients at the height of the pandemic in July.

Unlike seasonal influenza strains, which tend to hit elderly people and those of severe underlying health problems more heavily, many of those who became critically ill with the swine flu were babies and middle-aged people, pregnant women, the obese, Pacific Islanders, Māori and Aboriginal patients.

Rates of severe illness among Pacific people were seven times higher than the average, while those of Maori were twice as high.

[20] Following this plan New Zealand immediately upgraded its influenza pandemic alert status to code yellow.